Using Environmental and Biological Indices as Proxies for Egg and Larval Production of Marine Fish

Abstract

Several biological and environmental factors have direct or indirect influence on maturation, fecundity and egg viability of marine fishes. The relationships observed between these reproductive characteristics and specific biological and/or environmental indices may provide alternative methods of estimating annual variations in the reproductive potential of fish stocks in the absence of specific data, or represent a more rapid and less costly method of monitoring egg production. The utility of these relationships to serve as proxies for egg production will depend on the predictive power of the relationships, the effort required to measure selected proxies, the scale of application, and the availability of pre-existing target data. We believe that alternative methods to measure reproductive output could be developed for some reproductive characteristics needed to estimate egg/larval production using data already available. This review, largely based on gadoid fish species, indicates that relationships between indices of nutritional condition (e.g. condition factor, liver index) and potential fecundity meet the criteria of predictability and low effort and thus are candidate proxies for measuring egg production. No relationship examined was a suitable proxy for egg/larval viability and age-and size-at-maturity. The development of alternative measures of reproductive characteristics of fish could result in more precise estimates of reproductive potential of fish stocks that could be used for hindcasting and predicting egg and/or larval production and viability.

Reproductive Characteristics of <i>Leuciscus vorax</i> (Heckel, 1843) from Al-Huwaiza Marshes Southern Iraq

“…Variations in fecundity among the same and different species are common phenomenon and differ from year to other Najim et al (2012). Many factors could be influenced fecundity; length, weight, age, food abundance, environmental factors and fish status (Lambert et al, 2003;Kamler, 2005). However, there is compatible with our finding in the present work in general trends and with the previous studies on represented species (Al-Selah et al, 2010;Oymak et al, 2011;Al-Selah et al, 2012;Duman and Gul, 2013).…”

“…Caloric value of oocyte yolk which is largely associated of content water, lipids and protein that enables the larvae to pass the critical stage in their life history (Kamler, 2005). Yolked oocyte diameter is largely governed by the natural size of species attained, environmental conditions, reproductive strategy, spawning pattern and parental care (Lambert et al, 2003).…”

Available Information for Estimating Reproductive Potential of Northwest Atlantic Groundfish Stocks

“…However, the quality of existing data generally is high and the data for some gadoid and flatfish stocks may be sufficient to consider variability in fecundity between periods or to establish relationships with environmental variables that might be used to hindcast fecundity. Fecundity is generally affected by food ration and condition, and these factors have been used in developing predictive relationships of fecundity based on prey availability, growth/condition and temperature (Buckley et al, 1991;Kjesbu et al, 1998;Kraus et al, 2000;Lambert et al, 2003). However, the availability of condition data generally is low and only a few stocks possess sufficient data to establish time series.…”

“…Fulton's condition factor may be derived from length-weight data, but this condition factor is probably not the best indicator for fish species that primarily store their energy in the liver. For these species, the hepatosomatic index is a more accurate measure of condition (Marshall et al, 1999;Lambert et al, 2003). However, this indicator of condition is available for only a few of the examined stocks (Tyler and Dunn, 1976;Dutil, 1997, 2000).…”

“…The importance of various SRP parameters differs among stocks and in some cases, key variables may be applied as alternative SRP indices to improve stockrecruitment relationships (Marshall et al 2000;Lambert et al, 2003). Bioenergetic indices represent one such alternative metric (Ware, 1980;Lambert and Dutil, 1997;Marshall et al, 1999), while in other cases, age diversity indices might be a useful generalized indicator for spawner characteristics (Marteinsdottir and Thorarinsson, 1998;.…”